Copy testing is the process of studying an advertisement before it is being aired to find out how the customers will respond to that ad and hence determine its effectiveness. It is specialized field of marketing research that encompasses all media like television, radio, print ads and Internet. Pre-testing very often is considered as the most accurate and modern name for predicting how effectively any ad may perform. These predictions are based upon viewers' feedback about the ad. Each evaluation of the ad would either designate the ad as strong or as weak. If it rated strong then it is considered good enough and will meet company's ambition, on the other hand if it is rated weak in the standards of airing, then it is edited in order to improve its performance.Pre-testing also has auxiliary usage like it is often used as an identifier of weak spots in the ad campaign, or to most effectively structure the airtime slots to split the sixty second advertisements to thirty second advertisements. It can also be used to choose some images that can be used in integrated print ads. It may be used for extraction of key moments that can be used for ad tracking but also for identification of key branding moments.

The Positioning Advertising Copy Testing or PACT Principles are the guidelines that constitute a good or great copy test system.

PACT has laid down the following criterion for copy testing systems:

It has standardized and laid down some metrics that may be relevant to the overall target of the ad

It provides information about the usage of the results found during this phase.

Multiple measurements are made for greater accuracy as single measurements may fall short for evaluating the ad performance.

Copy testing be done in many ways but all the ways have the same three elements. The first element is the most important i.e. the selection of a group of people that are chosen as target audience who are asked a series of questions about the product or service. Second element being the exposure of the select group to a bunch of ads, one of which is the ad being tested and the last one is to follow up questions that were asked about the product.

After a successful phase of copy testing, advertising campaigns often need to be revised or corrected. It is believed that copy testing ensures that an advertising agency will be able to lower the chances of thwarting a successful advertisement campaign.